Dramatic e-cig explosion in New York

degarb

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BMS is a battery manager (battery management system) which may have either microcontroller chip (hence managed by software flashed thereon) or simple finite state machine in cheaper Lithium-ion cell protection chip. Since microcontroller is now cheaper than the simpler Lithium-ion cell protection chip, it's now used pretty often in larger battery pack.

Very familiar with cell chip protection. But, I am not with microcontroller chip. I assume the microcontroller chip is used like the protection chip on each cell, except can be programmed for a higher C and used for vaping cells that can handle insane current for an insane hobby.?.? Off to google that one.

One next single cell build, I was thinking of building in a volt readout of the protected (panasonic chipped cell), which are cheap. Just not sure of form factor, with usb charging.
 

Dr. Mario

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Microcontroller is kind of like a embedded computer that is programmed to do limited functions such as battery protection in this case - it's better to use microcontroller chip for multi-celled battery pack as it can track battery life better by keeping the batteries inside the pack balanced.

As for voltage readout, I suggest to get 2.5 - 30 Volts LED voltmeter which can be had from Amazon as they tend to be accurate as far as loaded voltage readout is concerned, just don't leave the LED voltmeter plugged in for too long as the circuit breaker in the protected Lithium-ion battery tend to trip at 2.8 Volts, in other word the circuit breaker board is only implemented as a last resort.

Much of the LED driver board for the DIY flashlights have microcontroller chip, and I strongly recommend that it be used as you can get low voltage protection programmed into, and LED drivers in my DIY flashlights all cut out at 3.0 Volts.
 

degarb

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What is the source, brand, cost, size, setup programming, attachment scheme of these micro controllers? I am guessing their benefit may be in that they may allow a higher C customization for the nickel laced flavored cell. Obviously, integration into a device.

For those reading, I will describe a protection circuit. Just easier to buy protected 18650. Unless you accidentally aquire unprotected cells. But fast tech has dime sized protection circuits (short,hi/low voltage protection) made to affix to negative of cell, with flat wire to attach to positive for voltage check. The catch is you must tack weld them on. Which you might get your local batteries plus guy to do. Or make your own from a microwave. Soldering onto liion will damage the cell. Anyway, impossible on negative end..... I believe nearly all cell explosions happen on unprotected or fairly protected cells. Puncture, crushing, stabbing, nawing, external heat, excepted.

I really believe in triple redundant protection,at a minimum.
 
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Dr. Mario

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Capacitor discharge welding is pretty common way to weld Nickel tabs on the batteries, however some people have successfully done that with modified 140 Watts soldering gun - basically redirecting 1 Volt AC into the welding tabs instead of solid soldering tip.

As for microcontroller, you have so much favors, from ancient Intel 8051, up to ARM Cortex M3 (and for more extensive application such as Internet of Things, superscalar out-of-order PowerPC and superscalar in-order Cortex M7 based microcontroller are therefore used there) - you also have variety of packages too. You make the call as far as hardware specifications are concerned.

The reason microcontroller is useful for both DIY battery pack and LED driver is because what you or the other have written in the assembler or C++ compiler tell the CPU core inside it what to do, and it has an advantage of reducing the number of chips that could have done the same thing - not to mention that there can also be transparent voltmeter telemetry from the battery pack so you can find out if the cells are still healthy.

And for sure I will use microcontroller chip in my battery pack as I want to be 1,000% sure I don't get trouble from it (and 90 - 45 nanometers microcontrollers consume very small current, about 100 microamps to 1 milliamp which is not a big deal, and ARM Cortex M3 microcontroller can actually shut itself down if the battery pack get to deep discharge voltage level - about 2.8 Volts - and rebooted when the charger plugs into the battery pack so it can continue to monitor battery condition and recharging cycle is usually dangerous time so it have to be sure nothing go wrong and Cortex M3 microcontroller can only be a buck so I can get the Lithium-ion fuel gauge for almost free in term of on-die ADC and software as a side advantage). And Mouser and a few other electronic component resellers usually sell them, however you have to know how to design the circuitry and Lithium-ion cell protection circuitry has to be reviewed twice to make sure you don't miss a thing which could be disastrous.

However, for some vapers, you would notice that not all makers bother to incorporate the battery protection system whatsoever (cigarette style is much worse in this regard).
 
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